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Created page with '===Overview=== *Gram positive bacteria *Grow slowly on media and produce branching filaments *Opportunistic infections causing inflammatory responses and granulomatous reaction…'
===Overview===
*Gram positive bacteria
*Grow slowly on media and produce branching filaments
*Opportunistic infections causing inflammatory responses and granulomatous reactions
*Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
===''Arcanobacterium, Actinomyces'' and ''Actinobaculum'' species===
*Non-motile, non-spore-forming bacteria
*Anaerobic or facultative anaerobes
*Grow on enriched media; non-acid fast
*Colonise mucous membranes
*Modified Ziehl-Neelson negative
===''Arcanobacterium pyogenes''===
*Characteristics:
**Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
**Small facultatively anaerobic rod
**Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
**Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
**Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
**Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
*Pathogenicity''
**Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
**Extracellular toxins including haemolysin, proteases, DNase and neurominidase
**Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells; dermonecrotising activity
*Clinical infections:
**Suppurative infections
**Abscesses especially in liver
**Lymphadenitis, [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
**Pyometra
**Endometritis
**Summer mastitis
**Ovine foot disease
**[[Joints Inflammatory - Pathology#In Sheep|Arthritis]] of sheep post-dipping; [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
**Umbilical infections
**[[Respiratory Bacterial Infections - Pathology#Acute exudative pneumonia|Acute exudative pneumonia]] and contributes to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
**May cause [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
**Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons Inflammatory - Pathology#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
*Treatment:
**Penicillin or broad spectrum antibiotics
===''Actinomyces''===
*Usually long filamentous branching Gram positive rods
*Anaerobic or facultativlyy anaerobic and capnophilic
*Live in nasopharyngeal and oral mucosa
*Cause pyogranulomatous lesions
**''Actinomyces bovis''
***Found naturally in oral cavity of cattle
***Prefers anaerobic conditions but not strict anaerobe
***Entry of organism into tissues following trauma to the mucosa from rough feed or tooth eruption
***Causes [[Chronic Inflammation - Pathology#Granulomatous Inflammation|granulomatous inflammation]] of soft tissues and bone, causing [[Teeth - Pathology#Mandibular Osteomyelitis|lumpy jaw]]
***Usually invades mandible to cause [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]] and may extend to surrounding [[Muscles Inflammatory - Pathology#Actinomycosis bovis|muscles]]
***The lesions begins as a painless swelling of the affected bone
***Swelling becomes more painful and enlarges over a number of weeks, gaining fistulous tracts which discharge pus
***Organisms found in yellow sulphur granules
***Club colony formation
***Colonies adhere to agar media and are non-haemolytic
***Surgical treatment possible when lesions are small
***Prolonged parenteral penicillin treatment may be beneficial early in the disease
**''Actinomyces viscosus''
***Commensal of oral cavity of dogs and humans
***Canine actinomycosis
***Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal ([[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]) and pleural surfaces in dogs
***Leads to [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
***Respiratory distress
***[[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|Cutaneous pustules]] in horses
***Abortion in cattle
***Rods contained in soft grey granules which release the organism when squashed
***Two types of colonies: large and smooth colonies with V, Y and T configurations or small and rough colonies with short branching filaments
***Grow in 10% carbon dioxide
***Usually responds to penicillin
**''Actinomyces hordeovulneris''
***Organism found in seed heads of certain grasses
***Colonies adhere to agar and are non-haemolytic
***Filamentous, branching organisms
***Cause [[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|cutaneous]] and visceral abscessation, pleuritis, peritonitis and arthritis in dogs
===''Actinobaculum suis''===
*Found in preputial mucosa of healthy boars
*Anaerobic
*Coryneform morphology
*Produces urease
*3mm diameter colonies with shiny raised centre and dull edge
*Disease transmitted at coitus
*Sows develop disease within 3-4 weeks of mating
*Produces lesions in urinary tract of sows
*Cystitis and pyelonephritis in sows
*Anoreixa, arching of back, dysuria and haematuria
*May be fatal
===''Nocardia''===
*Facultative intracellular bacterium
*Aerobic short branching rods
*Non-motile
*Spores from aerial filaments when cultured
*Grow on Sabouraud dextrose agar
*Cell wall contains mycolic acids (hence slightly acid fast)
*''Nocardia asteroides''
**Found in soil and decaying vegetation - saprophytic
**Opportunistic infection of immunocompromised animals
**Infection via inhalation, wounds or teat canal; also ingestion
**Causes granulomatous lesions in animals
**Canine nocardiosis:
***Thoracic, [[Bacterial skin infections - Pathology#bacterial granulomatous dermatitis|cutaneous]] and disseminated forms
***Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
***[[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]
***[[Respiratory Bacterial Infections - Pathology#Nocardiosis|pleuritis]] and pyothorax with fever, anorexia and respiratory distress
***Disseminated lesions
***Treat with appropriate systemic antibiotics for 6 weeks
**Cattle: chronic mastitis; abortion
**Pigs: abortion
**Sheep, goats, horses: wound infections; mastitis; pneumonia
**Survives and multiplies in macrophages
**Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
**Chronic, progressive disease
**Positive modified Ziehl-Neelson
**Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
**White, powdery colonies, adherent to the agar appear after 5 days
**Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
**Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
**Cell-mediated immunity required
*''Nocardia farcinica'' causes bovine farcy, a chronic infection of superficial lymphatic vessels and lymph nodes
===''Dermatophilus congolensis''===
*Filamentous, branching actinomycete
*Aerobic
*Produces motile zoospores
*No growth on Sabouraud dextrose agar
*Dermatophilosis most prevalent in tropical and subtropical regions
*Organisms found in scabs and in foci in skin of carrier animals
*Dormant zoospores become activated when moisture and temperature levels are favourable
*Zoospores may survive 3 years in scabs
*'''Pathogenicity''':
**Does not usually invade healthy skin
**Entrance after trauma or persistent wetting
**Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
**Invasion causes an accute inflammatory response with many [[Neutrophils - WikiBlood|neutrophils]]
**Microabscesses are formed in the skin
**Raised crusts develop in the affected regions
*[[Bacterial skin infections - Pathology#Dermatophilosis|'''Pathology''']]
*'''Diagnosis''':
**Giemsa-stained smears from scabs reveal branching filaments containing zoospores
**Immunofluorescence
**Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
**Zoospores can be cultured
**After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
**No growth on Sabouraud dectrose agar
*'''Clinical infections''':
**Infection usually confined to epidermis
**Dermatophilosis
**Disease most prevalent in young animals
**Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
**Lesions after heavy rainfall predominantly affect dorsum of farm animals
**Papules, serous, exudative matting of hair, raised crusty scabs
**Scab formation more prominent in sheep and cattle than in horses
**Lesions may resolve within weeks if dry weather, or may progress
*'''Treatment''':
**Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations
*''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and Bronchioles Inflammatory - Pathology#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
*''Thermactinomyces vulgaris'' may cause [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
[[Category:Bacteria]]
*Gram positive bacteria
*Grow slowly on media and produce branching filaments
*Opportunistic infections causing inflammatory responses and granulomatous reactions
*Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
===''Arcanobacterium, Actinomyces'' and ''Actinobaculum'' species===
*Non-motile, non-spore-forming bacteria
*Anaerobic or facultative anaerobes
*Grow on enriched media; non-acid fast
*Colonise mucous membranes
*Modified Ziehl-Neelson negative
===''Arcanobacterium pyogenes''===
*Characteristics:
**Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
**Small facultatively anaerobic rod
**Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
**Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
**Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
**Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
*Pathogenicity''
**Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
**Extracellular toxins including haemolysin, proteases, DNase and neurominidase
**Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells; dermonecrotising activity
*Clinical infections:
**Suppurative infections
**Abscesses especially in liver
**Lymphadenitis, [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
**Pyometra
**Endometritis
**Summer mastitis
**Ovine foot disease
**[[Joints Inflammatory - Pathology#In Sheep|Arthritis]] of sheep post-dipping; [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
**Umbilical infections
**[[Respiratory Bacterial Infections - Pathology#Acute exudative pneumonia|Acute exudative pneumonia]] and contributes to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
**May cause [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
**Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons Inflammatory - Pathology#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
*Treatment:
**Penicillin or broad spectrum antibiotics
===''Actinomyces''===
*Usually long filamentous branching Gram positive rods
*Anaerobic or facultativlyy anaerobic and capnophilic
*Live in nasopharyngeal and oral mucosa
*Cause pyogranulomatous lesions
**''Actinomyces bovis''
***Found naturally in oral cavity of cattle
***Prefers anaerobic conditions but not strict anaerobe
***Entry of organism into tissues following trauma to the mucosa from rough feed or tooth eruption
***Causes [[Chronic Inflammation - Pathology#Granulomatous Inflammation|granulomatous inflammation]] of soft tissues and bone, causing [[Teeth - Pathology#Mandibular Osteomyelitis|lumpy jaw]]
***Usually invades mandible to cause [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]] and may extend to surrounding [[Muscles Inflammatory - Pathology#Actinomycosis bovis|muscles]]
***The lesions begins as a painless swelling of the affected bone
***Swelling becomes more painful and enlarges over a number of weeks, gaining fistulous tracts which discharge pus
***Organisms found in yellow sulphur granules
***Club colony formation
***Colonies adhere to agar media and are non-haemolytic
***Surgical treatment possible when lesions are small
***Prolonged parenteral penicillin treatment may be beneficial early in the disease
**''Actinomyces viscosus''
***Commensal of oral cavity of dogs and humans
***Canine actinomycosis
***Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal ([[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]) and pleural surfaces in dogs
***Leads to [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
***Respiratory distress
***[[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|Cutaneous pustules]] in horses
***Abortion in cattle
***Rods contained in soft grey granules which release the organism when squashed
***Two types of colonies: large and smooth colonies with V, Y and T configurations or small and rough colonies with short branching filaments
***Grow in 10% carbon dioxide
***Usually responds to penicillin
**''Actinomyces hordeovulneris''
***Organism found in seed heads of certain grasses
***Colonies adhere to agar and are non-haemolytic
***Filamentous, branching organisms
***Cause [[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|cutaneous]] and visceral abscessation, pleuritis, peritonitis and arthritis in dogs
===''Actinobaculum suis''===
*Found in preputial mucosa of healthy boars
*Anaerobic
*Coryneform morphology
*Produces urease
*3mm diameter colonies with shiny raised centre and dull edge
*Disease transmitted at coitus
*Sows develop disease within 3-4 weeks of mating
*Produces lesions in urinary tract of sows
*Cystitis and pyelonephritis in sows
*Anoreixa, arching of back, dysuria and haematuria
*May be fatal
===''Nocardia''===
*Facultative intracellular bacterium
*Aerobic short branching rods
*Non-motile
*Spores from aerial filaments when cultured
*Grow on Sabouraud dextrose agar
*Cell wall contains mycolic acids (hence slightly acid fast)
*''Nocardia asteroides''
**Found in soil and decaying vegetation - saprophytic
**Opportunistic infection of immunocompromised animals
**Infection via inhalation, wounds or teat canal; also ingestion
**Causes granulomatous lesions in animals
**Canine nocardiosis:
***Thoracic, [[Bacterial skin infections - Pathology#bacterial granulomatous dermatitis|cutaneous]] and disseminated forms
***Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
***[[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]
***[[Respiratory Bacterial Infections - Pathology#Nocardiosis|pleuritis]] and pyothorax with fever, anorexia and respiratory distress
***Disseminated lesions
***Treat with appropriate systemic antibiotics for 6 weeks
**Cattle: chronic mastitis; abortion
**Pigs: abortion
**Sheep, goats, horses: wound infections; mastitis; pneumonia
**Survives and multiplies in macrophages
**Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
**Chronic, progressive disease
**Positive modified Ziehl-Neelson
**Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
**White, powdery colonies, adherent to the agar appear after 5 days
**Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
**Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
**Cell-mediated immunity required
*''Nocardia farcinica'' causes bovine farcy, a chronic infection of superficial lymphatic vessels and lymph nodes
===''Dermatophilus congolensis''===
*Filamentous, branching actinomycete
*Aerobic
*Produces motile zoospores
*No growth on Sabouraud dextrose agar
*Dermatophilosis most prevalent in tropical and subtropical regions
*Organisms found in scabs and in foci in skin of carrier animals
*Dormant zoospores become activated when moisture and temperature levels are favourable
*Zoospores may survive 3 years in scabs
*'''Pathogenicity''':
**Does not usually invade healthy skin
**Entrance after trauma or persistent wetting
**Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
**Invasion causes an accute inflammatory response with many [[Neutrophils - WikiBlood|neutrophils]]
**Microabscesses are formed in the skin
**Raised crusts develop in the affected regions
*[[Bacterial skin infections - Pathology#Dermatophilosis|'''Pathology''']]
*'''Diagnosis''':
**Giemsa-stained smears from scabs reveal branching filaments containing zoospores
**Immunofluorescence
**Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
**Zoospores can be cultured
**After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
**No growth on Sabouraud dectrose agar
*'''Clinical infections''':
**Infection usually confined to epidermis
**Dermatophilosis
**Disease most prevalent in young animals
**Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
**Lesions after heavy rainfall predominantly affect dorsum of farm animals
**Papules, serous, exudative matting of hair, raised crusty scabs
**Scab formation more prominent in sheep and cattle than in horses
**Lesions may resolve within weeks if dry weather, or may progress
*'''Treatment''':
**Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations
*''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and Bronchioles Inflammatory - Pathology#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
*''Thermactinomyces vulgaris'' may cause [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]
[[Category:Bacteria]]